Hongyuan Shao

Chitosan as a functional additive for high-performance lithium–sulfur batteries

Chitosan with abundant hydroxyl and amine groups as an additive for cathodes and separators has been proven to be an effective polysulfide trapping agent in lithium–sulfur batteries. Compared with common sulfur cathodes, the cathode with chitosan shows an enhanced initial discharge capacity from 950 to 1145 mA h g−1 at C/10. The reversible specific capacity after 100 cycles increases from 508 mA h g−1 to 680 mA h g−1 and 473 to 646 mA h g−1 at rates of C/2 and 1 C, respectively. In addition, batteries with separators that are coated with a carbon/chitosan layer can exhibit a high discharge capacity of 830 mA h g−1 at C/2 after 100 cycles and 675 mA h g−1 at 1 C after 200 cycles with the capacity fading to as low as 0.11% per cycle. This study demonstrates the benefits of using chitosan for not only lithium–sulfur batteries but also potentially other sulfur-based battery applications.

Modified Separator Using Thin Carbon Layer Obtained from Its Cathode for Advanced Lithium Sulfur Batteries

The realization of a practical lithium sulfur battery system, despite its high theoretical specific capacity, is severely limited by fast capacity decay, which is mainly attributed to polysulfide dissolution and shuttle effect. To address this issue, we designed a thin cathode inactive material interlayer modified separator to block polysulfides. There are two advantages for this strategy. First, the coating material totally comes from the cathode, thus avoids the additional weights involved. Second, the cathode inactive material modified separator improve the reversible capacity and cycle performance by combining gelatin to chemically bond polysulfides and the carbon layer to physically block polysulfides. The research results confirm that with the cathode inactive material modified separator, the batteries retain a reversible capacity of 644 mAh g(-1) after 150 cycles, showing a low capacity decay of about 0.11% per circle at the rate of 0.5C.

Crab shell-derived nitrogen-doped micro-/mesoporous carbon as an effective separator coating for high energy lithium–sulfur batteries

Lithium–sulfur (Li–S) batteries with high energy density are considered as promising for rechargeable energy storage. However, the shuttle effect hinders their practical application. Here, novel nitrogen-doped micro-/mesoporous carbon (N-MIMEC), derived from crab shells, was fabricated via a sustainable and cost-effective route. A modified separator coated with an N-MIMEC layer for Li–S batteries exhibits many advantages: (1) the micro-/mesopores provide enough surface area for sulfide adsorption, and accommodate the volume change; (2) the nitrogen in N-MIMEC enhances polysulfide adsorption and increases the electronic conductivity of the carbon framework; and (3) the conductive layer acts as an upper current collector, increasing the electrical conductivity. An enhanced Li–S battery with an N-MIMEC-coated separator was constructed, with an initial capacity of 1301 mA h g−1 and a high reversible capacity of 971.3 mA h g−1 after 100 cycles at 0.1C. Also, upon further increasing the sulfur loading from 63 wt% to 77 wt%, the corresponding Li–S batteries exhibit a high reversible capacity of 578 mA h g−1 after 500 cycles at 1C, with a decay rate of about 0.029% per cycle. Considering the green and sustainable source material, simple preparation and good electrochemical performance, the N-MIMEC-coated separator is promising for Li–S battery applications.

From fish scales to highly porous N-doped carbon: a low cost material solution for CO2 capture

This article reports a strategy to use fish scales as raw materials for synthesizing CO2 capture materials. The synthesis employs thermal and chemical treatment to convert fish scales into N-rich porous carbons. The proteins in the fish scales are the major source of carbon and nitrogen. By varying the reaction conditions, the porosity and N content can be controlled in the produced porous carbons. It was found that the porosity first increases and then decreases with an increase in thermal treatment temperature; the N content decreases with an increase in the temperature. The capture capacity of the as-synthesized carbon (NFPC-750) for CO2 can be up to 171 mg g−1 at 25 °C, 1 bar. This high capacity is attributable to its porous structure with a high specific surface area (up to 3206 m2 g−1) and large pore volume (micropore volume up to 0.76 cm3 g−1 and total pore volume up to 2.29 cm3 g−1). More attractively, quaternary nitrogen is effectively preserved (2.90% N), which should be another contributor to enhance the CO2 capture capacity through the chemical adsorption between nitrogen groups and CO2. In addition, the sorbent preliminarily exhibits high cycle stability with retention of 91.8% of its initial CO2 capacity after 10 cycles. This highly porous N-doped porous carbon obtained from fish scales is thus considered a promising material for CO2 capture.

High-performance fish-scale-based porous carbon for the removal of methylene blue from aqueous solution

The adsorption of methylene blue (MB) from aquatic systems by the fish-scale-based hierarchical lamellar porous carbon (FHLC) was investigated. In this paper, the FHLC was used as an alternative adsorbent to replace the Norit CGP, a commercial activated carbon, and showed an overall fast and pH-dependent MB adsorption. The effect of contact time, pH and concentration on MB adsorption was investigated. It was found that the adsorption behaviours of FHLC and CGP could be described by a monolayer Langmuir type isotherm. The kinetic data followed the pseudo second-order kinetic model for both activated carbons as the linear correlation coefficients were all above 0.9999. Thermodynamic analyses indicated that the adsorption was an endothermic and spontaneous physisorption process. The maximum Langmuir adsorption capacity of the FHLC was 555.55 mg g−1 at pH = 7.07 and 1050.72 mg g−1 at pH = 11.00 while that of the CGP was 432.90 mg g−1 at pH = 7.07 and 649.35 mg g−1 at pH = 11.00, respectively. The adsorption capacity of the FHLC was much better than that of the CGP at different pH values. Our study shows that fish-scale-based carbon could be used as a high-performance and cost-effective adsorbent to remove MB in aqueous solution in the wastewater treatment.

Development of a γ-polyglutamic acid binder for cathodes with high mass fraction of sulfur

Lithium–sulfur (Li–S) batteries have been one of the most attractive secondary battery systems to take advantage of their high theoretical energy densities and the low cost of sulfur. However, to realize their wide-scale commercial use, a high sulfur fraction is essential for the sulfur cathode. It is well known that the binder has a direct impact on the properties of the sulfur cathode. In this paper, γ-polyglutamic acid (PGA) was adopted as a functional binder in Li–S batteries. With plentiful electron-rich groups (amide, carboxyl) in the PGA molecular chain, the shuttle effect was restrained, and a good conductive network was formed. It was found that batteries using PGA as a binder exhibited better electrochemical cycling performance and rate capability compared to batteries using LA132, a common binder in sulfur cathodes. Even the PGA cathode contained a high sulfur mass fraction (77 wt%), the discharge capacity still remained 659 mA h g−1 with a coulombic efficiency of around 99% after 200 cycles at 0.5C.

Antibacterial Activity and Physical Properties of Fish Gelatin-Chitosan Edible Films Supplemented with D-Limonene

Fish gelatin-chitosan edible films with D-limonene were successfully prepared, which exhibited exceptional mechanical properties and antimicrobial activity. It has been demonstrated that water-soluble chitosan, fish gelatin, and D-limonene could be a candidate precursor to prepare low cost and high-performance edible food packaging material. The results showed that D-limonene in the films could effectively resist the penetration of light and water because of its hydrophobicity. Moreover, the elongation at break (EAB) increased with the addition of D-limonene, which indicated that D-limonene served as a strong plasticizer for the film. Microscopic characterization showed that D-limonene was uniformly distributed in the as-prepared film. And we found that the film exhibited strong antibacterial activity against Escherichia coli (E. coli). All the results indicate that the as-prepared film could be a promising food packaging.